1. Field of the Invention
A catheter device primarily designed for the catherization of a predetermined blood vessel during the process of hemodialysis and structured to have the operating characteristics which include continuous flow of blood to and from the vessel through fluid segregated flow paths both positionable into the predetermined blood vessel by a single puncture.
2. Description of the Prior Art
At the present time it is well accepted medical practice in the performance of both emergency and cronic hemodialysis to utilize two separate catheters in the blood vessel or vessels being catherized. Each of the catheters are placed separately requiring at least two "sticks" or punctures of the body of the patient. These plurality of punctures required in the placement of the separate catheters is naturally accompanied by the usual pain and discomfort to the patient. Placement of the individual catheters is accomplished commonly by the Seldinger technique.
The Seldinger technique involves the perforation of a vein with a hollow needle. A flexible wire is then threaded through the needle and up the vein. The needle is withdrawn over the wire and a plastic flexible catheter is slipped down over the wire using it as a guide for proper placement of the catheter on the interior of the blood vessel. A second catheter is then inserted in this same manner thereby requiring placement of two needles in the patient with the attendant pain as set forth above. Due to the fact that the second catheter is almost always more difficult to place than the first, especially when the catheters are placed at different levels in the same blood vessel, it is common for more than two "sticks" or perforations of the patient to be required. In addition, when placing the second catheter in the same blood vessel as the first catheter in relative adjacent location actual placement of the catheter is accomplished by the manipulation in somewhat of a twisting fashion. Frequently, this causes fouling or entanglement of the two catheters.
Accordingly, it can readily be seen that a single catheter device having equal or superior performance characteristics as that of two separate catheters would be highly desirable due to the reduction in pain and discomfort to the patient undergoing the dialysis treatment. Accordingly, the use of a coaxial flow catheter incorporating essentially inner and outer catheter tubes would naturally be more desirable since proper positioning of such a device could be accomplished with obviously less discomfort to the patient.
In fact, coaxial flow devices per se are available in the prior art for use in generally similar medical procedures.
For instance, the patent to Bennett, U.S. Pat. No. 3,670,729 is directed to a tranfusion needle wherein an inner elongated tube 22 is used to pass blood into a predetermined vessel in the human body. An outer, coaxial and concentrically arranged tube relative to the inner tube, is provided with pores in the external surface thereof so as to provide a cleansing or disinfecting fluid to the area of the puncture of the transfusion needle at the point of entry of the body. However, this structure is not designed to accomplish flow in the inner and outer tubes in opposite directions to accomplish delivery of blood to and from a blood vessel as required in hemodialysis treatment.
In the area of dialysis medical equipment has been developed which utilizes only a single catheter wherein blood is alternatively forced to and from the blood vessel of the body in which the catheter is placed through the utilization of relatively complex machinery which operates at questionable efficiency and relative great expense. Prior art devices of this type are generally represented in the patents to Lange, U.S. Pat. No. 3,520,298, and Kopp, U.S. Pat. No. 3,756,234.
However, as set forth above, devices generally representative of this type are frequently, due to their complexity, expensive to maintain and procure as well as being noisy in operation thereby adding to the discomfort of the patient during treatment.
Other devices known in the prior art which are designed for the transfer of fluid to and from the body are represented in the patent to Hsi Hu, U.S. Pat. No. 2,564,977. While devices of this type are not specifically directed to dialysis treatment they are directed to the transfer on a continuous or alternating basis of fluid to and from predetermined portions of the human body.
In spite of the existence of prior art and present commercially available devices there is still a need for medical apparatus in the form of a catheter device capable of efficient operation with minimum discomfort and pain to the patient. Ideally, such a device would be capable of continuous and concurrent flow of blood both to and from the patient.